Musical instrument



March 20, 1951 M. J. LARsEN MUSICAL INSTRUMENT 2 Sheets-Sheet 1 FiledAug. 5, 1949 Si@ n Tw w INVENTOR. AM/PW//VJ A/sfsf/v,

BY l

A frR/VE y M. J. LARSEN MUSICAL INSTRUMENT March 20, 1951 2 Sheets-Sheet2 Filed Aug. 5, 1949 Patented Mar. 20, 1951 MUSICAL INSTRUMENT Merwin J.Larsen, Villa Park, Ill., assignor, by

mesne assignments, to Central Comercial Industries, Inc., Chicago, Ill.,a corporation o Delaware Application August 5, 1949, Serial N o. 108,706

19 Claims.

This invention relates to electrical musical instruments of the classemploying sources producing complex audio signals at the tonefrequencies of different notes of the chromatic scale, which signals areadapted to be selectively translated into audible sounds in response toactuation of the playing-keys of a keyboard. An instrument of this classis fully disclosed in Letters Patent of the United States, No.2,403,090, granted to me on July 2, 1946.

In the aforementioned Letters Patent, the signal sources consist of highvacuum tubes, the complex output waves of which are conducted to wavefilters by means of which they are repeated as waves of differentharmonic composition and then impressed on the input circuit of anelectroacoustical translating device and reproduced as audible sounds ofdifferent timbre.

An essential object of the invention is the provision of an organizationof elements for producing pleasing sustained tones by an exceedinglysimple and inexpensive system of transmission and keying-circuits.

The herein disclosed embodiment of my invention employs sixty sourcesrespectively providing tone frequencies embracing a range of iiveoctaves, such that the lowest fundamental frequency is approximately 65.cycles per second. In organ nomenclature this range of sequentialfrequencies is known as a basic 8-foot stop. Most pipe organs embodt7what are known as couplers. These are designed so that tones in givenfrequency relation are available in diferent combinations, i. e. thebasic B-foot tone can be coupled to a tone which may either be a 4-foottone an octave above said basic tone or a 16-foot tone an octave belowsaid basic tone. With the organ, the player can selectively draw one ormore coupler stops as may prove most useful for musical expression.

It is well known that when a tone of a given fundamental pitch iscoupled to tones of other given pitch, the combination or resultant toneis more brilliant and has body the Single tone lacks. While a feature ofthe invention is a simple and inexpensive method of coupling octavelyrelated tones, the invention is not limited in this respect, for thereason that by very similar methods of coupling given frequency sourceswith each other, tones can be produced that are comparable to variousmixture stops of an organ. For example, the stop known as the manualquint 5%-foot which sounds a fifth above the normal pitch of an 8-footstop, or the octave quint which sounds a twelfth above an 8-foot stopcan be very readily obtained.

In an electrical musical instrument the addition of selectively actuablecoupler and mixture stops entails an expense that is prohibitive in aninexpensive instrument, and it is therefore a further object of myinvention to provide a simple system or method of permanently couplingto each other tones in any given pitch relation so that the resultanttones are more or less comparable to tones produced by more expensiveinstruments.

A still further object is the provision of a simple and inexpensivecoupling system for electrical musical instruments whereby tonal balanceor necessary tapering of the relative amplitudes of tones is assuredfrom top to bottom of the gamut, regardless of the pitch relation ofindividual tones comprising any given combination of tones.

A still further object is the provision of a system adapted to beembodied as integral parts of circuits of the various cascades ofelectron discharge devices employed herein for producing complexwaveforms at different tone frequencies and by means of which there willbe no robbing amongst frequencies drawn simultaneously from any singleelectron discharge device.

The novel features of my invention are set forth with particularity inthe herein appended claims. The invention, however, both as to theorganization of elements employed and the method of operation, togetherwith additional objects and advantages will be fully understood from thefollowing description of a specific embodiment of the invention taken inconnection with the accompanying drawings, in which:

The drawing is a schematic view of the invention, in which Figures l andla are continuations of a common electrical network when the figures arearranged to dispose Figure 1a, at the right of Figure 1.

In the production of musical tones from tone frequency sources orgenerators producing waveforms of audio signals which are rich inharmonics, it is customary to draw on one such source or generator onlyfor each basic note and ,to employ, in addition thereto, switching meansto draw upon sources or generators having octavely related (or othermultiple) frequencies. For example, in pipe and electronic organs,8-foot tones are keyed by means of straight-forward connections tosources or generators, the output frequencies of which correspond innumber to the vibration frequencies of notes associated with thedifferent playing-keys of a keyboard. li-foot tones are produced byselectively drawing frequencies from sources or generators one octavehigher than the basic 8-foot tones. l-foot tones are asiatica 3 producedby other switching means which draw upon sources or generators havingfrequencies one octave lower than the basic 8-foot tone. Similarcoupling switches can also, be arranged to draw upon sources orgenerators producing 2-foot tones (two Octaves higher) or 22/3-foottones can be Y produced by connections to sources or generators havingfrequencies nearest the third harmonic of the basic S-foot tone, and soon. In carrying my invention into practice, resort can be had to any ofthese coupling methods, and for the broad purpose of my invention, theterm coupling as used herein shall not be limited to the coupling ofoctavely related frequencies.

In order to produce a low-cost instrument with the maximum richness oftone, it is expedient in one embodiment of my invention to permanentlyconnect, in a special manner, the 4-foot and the iii-foot tones with thebasic S-foot tones, thereby eliminating otherwise expensive selectiveswitching and involved or complicated wiring and cabling. 'Io coupleboth 16-foot and 4-foot tones to 8-ioot tones from top to bottom of akeyboard having a range of ve octaves would require a number of sourceswhich would be greater than the number of playing-keys of a five octavekeyboard. In the instant embodiment of my invention, use is made of onlysixty sources or gen erators embracing a frequency range of iiveoctaves, and by tapering the amplitudes of the 16- foct outputs suppliedto the next-to-lowest octave keys and similarly tapering the amplitudesof the 4-foot outputs supplied to the next-to-highest octave keys, andomitting the l6foot coupling in the bottom octave and the 4-footcoupling in the top octave, highly satisfactory results are obtained,such that to the average ear it is diicult to discern the differencebetween this system of coupling and the more expensive system in whichfor each key in said keyboard there are three distinctive tones atoctave separation.

In the accompanying drawing, it is assumed that the keyboard of theinstrument has sixty playing-keys and that each separate key operates asingle electric switch. Fourteen of these switches are shown andrespectively designated KCI, KCtl-KCZ and KC5. Each separate switchcomprises a Xed contact element it connected to ground Il, a xed contactelement l2 connected to a. common output conductor i3 and a movablecontact element i4, the latter coactive with the key so that when thekey is fully eleN vated, the switch is ofi and contact element I4 isengaged with element It so that the current flow is to ground. Saidcommon conductor i3 is connected to ground by a resistor i3 of 4.7 K.When the key is depressed, the movable contact element I4 engagescontact element l2 and the switch is on The output conductor i3 connectsall of said switches with a iiltering system for producing a number oftone qualities. This system consists of lters I5, ll and I8, connectedby branch paths i9, 20 and 2i to said common conductor I3. The outputleads 22 `from said filters are each thereof provided with a controlswitch 23. These leads connect at 24 to the input lead 25 of an audioamplifier 26 in the output circuit of which is a loud speaker 2l. Theinput circuit of the amplifier is provided with any well known volumecontrol device 28.

The term generator as used herein shall mean any well known electronicor electrical device or source adapted to produce an output wave whichis rich in harmonics as distinguished from a single or sinusoidal wave.Systems of this class are shown in the patent to Larsen et al. No;2,410,883 and are entirely dependable for the pur pose of my invention.Said system consists of a plurality of sets of high vacuum tubes inwhich the tubes of each set are connected in cascade and function asfrequency dividers, i. e. assuming that the frequency of stage Cl of theC cascade is 1046. c/s, the frequencies of the successive, (controlled)stages of said C cascade will be 523., 262., 131., and 65. c/s, In thismanner, the outputs of the respective stages of each and every cascadewill be at octavely related frequencies. While the frequencies are notdivided exactly by a factor of 2 for each stage, the division issufciently accurate for all practical purposes.

In my Patent No. 2,403,099 twelve similar divider circuits are employed.Each separate circuit consists of a controlling stage oscillating at agiven natural frequency which corresponds to the vibration frequency ofthe highest note of a given letterA in the chromatic scale. Thus, thereis a circuit producing outputs corresponding to the tone frequencies ofall C notes, a circuit producing outputs at the tone frequencies of allCt notes, a circuit producing outputs corresponding to the tonefrequencies of all D notes, and so on, to and inclusive of a circuitproducing outputs at the tone frequencies of all B notes. As the rangeof the herein described instrument is limited to sixty notes, there willbevsixty individual oscillator stages or five stages per separatedivider circuit of the twelve similar circuits. In the herein disclosedembodiment of my invention, the twelve divider circuits are arranged inthree groups of four similar circuits, each, such that one groupconsists of circuits respectively producing outputs for all C, Ct, D andDit notes, a second group of circuits respectively producing outputs forall E, F, Ft and G notes and a third group of circuits respectivelyproducing outputs for all Gt, A, At and B notes. To avoid undulycomplicating the herein disclosed electrical network I have disclosedbut one circuit of each of said groups and have designated them Ccircuit, E circuit and G circuit.

Referring to the group comprising the C, Ct, D and Dt circuits, only theC circuit is shown. This comprises coupled stages Cl, C2, C3, C4 and C5.

Of the group comprising the E, RF1? and G cir cuits, the drawingsdisclose only the E circuit which comprises coupled stages E1, E2, E3,E4 and E5.

Of the third group which comprises circuits Gt, A, At and B, thedrawings disclosed only the Gt circuit, the same comprising stages Gti,GiiQ, Gt, Gilll and Gt.

Referring more particularly to the circuit comprising stages Cl, C2, C3JC4 and C5, it is noted that said stages respectively have outputterminals Ci', C2', C3', C4 and C5. Terminal CI has a resistance Rl inseries; terminal C2 a resistance Rd in series; terminal C3', aresistance Rl in series; terminal C-t, a resistance Rill in series;terminal C5', a resistance R83 in series.

The output of stage C2 is connected to terminal Cl and C3' by resistorsR3 and R5. The output of stage C3 is connected to terminals C2 and Cd byresistors R6 and R8. The output of stage C4 is connected to terminals C3and C5' by resistors R9 and Rl l, and as shown, the output of stage C5is connected to terminal Cd by resistor R i 2.

It follows from the above description that stages Cl and C5 are eachthereof provided with a potential divider comprising two branchresistive output channels through which portions of a waveform ofvoltage is adapted to be concurrently conducted and that each stage C2,C3 and C4 has a potential divider comprising three branch resistiveoutput channels. As each separate cascade of the twelve cascades hereinemployed is similarly designed, except as will be hereinafter pointedto, the resistances in the output channels of all similarly situatedstages are designated by like reference characters and numerals.

Referring now to the manner of connecting the various stages in a keyingand transmitting network, I have shown key-actuated switches of akeyboard employing sixty playing-keys. I have also shown a singlekey-actuated switch for the playing key for the last note in the topoctave. It is noted that terminal CI' connects to the movable contactelement I4 of switch KCI; that terminal C2 similarly connects withswitch KC2 an octave above KCI that terminal El' connects with switchKEI and that terminal Gill connects with switch KGiiI. It accordinglyfollows that from terminal CI there will be impressed on switch KCI awave which is the sum of the coupled outputs of stages CI and C2. StageCI provides a frequency equal to 65. cycles per second (basic 8-foottone) stage C2 producing a frequency equal to 131. cycles per second (anoctave above CI). Similarly, the El terminal from stages EI and E2impress on switch KEI a wave which is the sum of waves corresponding to8foot and 4-foot tones. In like manner, terminal Giil conducts to switchKGtI a wave which is the sum of 8-foot and 4-foot tones. In like mannerall remaining switches comprising the lowest octave will be similarlyconnected by their leads to their respective' stages.

Regarding the three intermediate octaves, each playing-key will besupplied with a wave which is the sum of -foot, 4-foot and 16foot tones.Only a connection to one switch, namely KC2 of the three intermediateoctaves is shown, but on referring thereto it is noted that terminal C2which connects therewith conducts thereto a wave which is the sum of theoutputs of stages CI, C2 and 0C3, whereby the resultant tone will be amixture of 4-foot, 8-foot and 16foot tones. All intermediate switchescomprising the three middle octaves will be similarly connected.

In order that there will be no robbing amongst divided portions of theoutput of any generator that is simultaneously drawn upon, theresistances in the output of each separate stage are high relative tothe internal impedance of said stage and the impedance of the loadcircuit.

An important feature of the invention is the herein disclosed use oftwelve divider or equivalent circuits for producing frequencies through-'out a useful musical range, which circuits are arranged in groups, suchthat each separate group comprises a given number of similar circuits.By this is meant that except that each separate circuit in any groupfurnishes its own or preassigned octavely related frequencies whichcorrespond to the vibration frequencies of notes of the same letter ofthe chromatic scale, the resistances, coupling and tapering andanti-robbing of all circuits comprising any group are of the samevalues. By the method employed the high frequency tone signals areincreased in amplitude by lowering, in groups, the values of resistorsRI 2 for the 4-foot outputs and RIS for the 8-foot outputs, whichincrease is necessary to compen- 6 sate for the wave lters I6, I1 and I8beyond the key switches.

The following table discloses the grouping of different sets of circuitsand the various values of resistances in the outputs of the differentstages:

Table of values and divider circuit grouping Group l Group 2 Group 3Footage Terminal Resistors C, C#, D, E, F, FSI, G#, A, A#,

D# G B l R1 470 K 470 K... 470 K 2 R4 470 K 470 K.-. 470 Kv 8-Ioot- 3 R7470 K. 470 K.. 470 K 4 R10 470 K 470 K. 470 K 5 R13 220 K 150 K 100 K 2R2 3.3 Meg 2.2 Meg 1.5 Meg. 164cm 3 R5 820K. 0K... 820K 4 R8 820 K. 820K. 820 K 5 Rll 820K 820 K U.- 820 K l R3 680 K 680 K 680K Moot 2 R6 680K. 680 K 680 K 3 R9 680 K 680 K. 680 K 4 R12 330 K- 220 K 150 K hK isused to designate one thousand ohms-i. e. 470 K=470,000 o ms.

l1lII/eg. is used to designate one million ohms-i. e. 1.5 Meg.=l,500,000o s.

While I have selected a practical grouping of the divider circuits, thetotal number of which consists of twelve such circuits arranged ingroups of four circuits each, this is by way of illustration and inorder that any person skilled in the art can satisfactorily practice theinvention. I do not intend, however, to be limited in this respect asthe number of individual tone frequencies comprising any group willdepend upon the number of octaves comprising a given note or frequencyrange, to which can be added the total number of outputs desired to beconnected to the keying circuits.

All of the aforementioned switches connect to the common output I3, sothat when any selected switch is in an on condition, the Output ofVgenerators associated with said switch will be impressed on the wavelter system, thence impressed on the input circuit of the poweramplifier 26 by selected actuation of the aforementioned switches 23.The wave filter system may be of any well known type so that theresultant tone will approximate a tone of any given timbre. The wavelter system shown and fully described in my Patent No. 2,403,090 isentirely suitable for the purpose of my invention.

The fundamental frequencies indicated upon the accompanying drawings arerelated to the standard frequency A=440 c/ s.

Particular Stress is placed upon these features of my invention whichconsist in providing a potential divider in the output of each separateelectron discharge device as provided for by the impedances in saidoutput.

As will be observed by referring to the table of values and dividercircuit grouping, the 16- foot signals supplying the next to lowestoctave switches are attenuated increasingly as the frequency lowers inthree steps, each step comprising four notes. In addition to providingtonal balance this feature serves to blend the amplitudes of the signalsso that no abrupt change is noticed at the junction where the 16footsignals are omitted, as between key KCI and key KC2.

At the other end of the keyboard, however, the 4-foot generator signalsare not attenuated. In fact, they are increased slightly, in groups,within the next to the lowest octave. The reason for this is that theattenuation in the further networks more than compensates for theincreasing generator signals.

Tone frequency sources as used herei-n shall be construed to mean anywell known electron discharge device or generator for producing anoutput wave of predetermined audio frequency which is preferably but notnecessarily a wave rich in its harmonic composition. a

While I 'have disclosed herein a system of frequency generatorsconsisting of separate frequency halving circuits, any of the wellyknown frequency multiplying circuits may be used to full advantage.

I claim:

1. A musical instrument of the class employing a keyboard, eachplaying-key of which is provided with a single electric switch which isactuable from an off condition when the key is elevated to an oncondition when the key is lowered; said instrument comprising aplurality of divider circuits, each comprising oscillator stagesconnected in cascade and including a controlling first stage operatingat a given natural frequency and a plurality of controlled stages, saidcontrolling stage and said controlled stages respectively producingoutput Waves at octave separation and each having an output terminalpermanently connected to an assigned one of said switches; andimpedances in each separate divider circuit, Isaid impedances connectingpreassigned stages with preassigned output terminals, whereby the waveimpressed on any single terminal and on any single electric switch isthe sum of output Waves of at least two of said stages.

2. A musical instrument of the class employing a work circuit, and akeyboard, each playing-key of which is provided with a single electricswitch which is actuable from an Off condition when the key is elevatedto an on condi-tion when the key is lowered; said instrument comprisinga plurality of sources respectively producing output waves at tonefrequencies for more than two cctaves of notes of a musical scale, eachof said source having an output terminal permanently connected to apreassigned one of said switches and v provided with an impedance ofgiven value, said source also having an output path in addition to thepath provided by said terminal, the same connected to theoutput terminalof another one of said sources, whereby in addition to conduction of theoutput from any source to a pre assigned switch there is conducted tothe same switch the output wave from ancther source.

3. A musical instrument as set forth in claim'2, wherein the additionaloutput path yfrom each separate source has an impedance, the value ofwhich is different from that of theirnpedance of the output terminal ofthe same source.

4. A musical instrument as set forth in claim 2, wherein the additionaloutput path from each Aseparate source has an impedance, the value ofwhich is different from that of the impedance of the output terminal ofthe same source and wherein both said impedances are high `relative tothe impedance of said source.

5. An electrical musical instrument of the class employing a workcircuit and a keyboard, each separate playing key of which is providedwith a single electric switch which is actuable thereby from an ocondition when the key is elevated to an on condition when the key islowered; said instrument comprising a plurality of sources respectivelyproducing complex output waves at tone frequencies for more than twooctaves of notes of a musical scale, each vof said sources having 1anoutput terminal permanently connected to a preassigned one of saidswitches and `provided with 'animpedance of predetermined value, saidsource'also having an output path in addition to the path provided bysaid terminal and having an impedance of predetermined value, saidadditional path connected to the output terminal of another one of saidsources, whereby in addition to conduction of the output from anysourcevto a preassigned switch there is conducted to the same switch theoutput wave from another source, said switches connected with said loadcircuit and said impedances in the paths of any source, each being highrelative to the impedance -of said source and the impedance of said loadcircuit.

6. `An electrical musical instrument as set forth in claim 5, whereinsaid work circuit includes means `for repeating the output of Wavesfimpressed thereon as waves differing therefrom in their harmoniccomposition.

'7. An electrical musical instrument as set forth in claim 5, whereinsaid work circuit includes means for repeating output waves `impressedthereon as waves differing therefrom in their harmonic composition andwherein said work circuit has means for translating said repeated wavesinto audible sounds and of desired volume.

8. rA musical instrument of the class employing a keyboard, eachplaying-key of which vis `provided with a single electric switch,actuable b'y the key from an oi condition ofthe switch when the key iselevated to an onf condition thereof when the key is lowered; saidinstrument comprising a plurality of sources of complex audio signalshaving the vibrationffrequencies of different notes of a musical scale,impedances connecting eachseparate switch to preassigned ones of saidsources, and means including'a conductor connected in common lto all ofsaid switches for transmission of signals to an electroacousticaltranslating system.

9. A musical instrument as setforth in claim', wherein said sourcescomprisehigh vacuum tubes providing separate sets of tubes in which 'thetubes of each set are connected in cascade and aration.

10. In va musical instrument employing wave filters and sourcesrespectively vproducing compleX waveforms of audio signalshaving thetone frequencies of different notes of a musical scale, a playing-keyactuated switch -for and connected to each separate one of theaforementioned sources, impedances coupling preassigned sourceswithpreassigned switches such that signal Voltages conducted to anyindividual switch is the sum of signal voltages from'respective sources,a common conductor connected 'to 'all of said vswit'chesand. tosaidfilters, and'means enabling selective conduction of the outputs ofsaidiilt'ers to the input circuit of anelectroacoustical translatingsystem.

l1. A musical instrument as set forth inclailn 10, wherein the values ofsaid impedances are such thatithe'relative amplitudes of lsignalvvvoltages conductedto `a switch` from coupied sources are relativelydifferent.

l2. vIn a musical instrument employing sources respectively producingaudio-signals `at the tone frequencies of sequentially related tonesignals for arrange of more than two octaves; said in strumentcomprising in Vconflbination `with each separate one of said sources asingle electric switch adapted to be actuated by a playing-key of akeyboard, impedances of predetermined values coupling the outputs ofpreassigned sources to preassigned switches such that there isselectively impressed on any single switch at least two signals ofdifferent frequency, said impedances serving to x the amplitude relationbetween signals of different frequency impressed on any switch.

13. In a musical instrument of the class em-V ploying a keyboard, eachplaying-key of which is provided with a single electric switch actuablefrom an off condition when the key is elevated to an on condition whenthe key is lowered, said instrument comprising a plurality of sources ofaudio signals having the vibration frequencies of musical notes for arange of more than two octaves, each of said sources having a potential`divider providing a plurality of parallel paths,

each having an impedance of predetermined value, a switch for andindividual to each of the sources, said paths connecting individualswitches ,with a plurality of preassigned sources such that ythere isimpressed on each individual switch a waveform of voltage which is thesum of signal voltages from said plurality of sources, the values ofsaid impedances in said voltage dividers being predetermined so that theamplitude of one frequency component impressed on a switch is greaterthan that of another frequency component impressed on the same switch.

14. A musical instrument as set forth in claim 13, wherein a loadcircuit is included and a common conductor connects all of said switchesto said circuit, the impedance of said load circuit 4being low relativeto the impedances in said parallel paths.

15. A musical instrument as set forth in claim l 13, wherein saidsources are connected in sets in which the sources of each separate setare coupled in cascade.

16. A musical instrument of the class employing a keyboard, eachplaying-key of which is provided with a single electric switch which isactuable thereby from an off condition when Vthe key is raised to an oncondition when the key is lowered; said instrument comprising as manytone frequency sources as there are playing-keys in said keyboard, eachof which produces an audio signal corresponding to the vibrationfrequency of the note associated with a preassigned playing-key, anelectrical network in which said switches and said sources areconnected, said network including output terminals permanentlyconnecting given lcries of said vsources to switches of preassignedplaying-keys of said keyboard, paths connecting preassigned assignedones of said devices with preassigned ones of said terminals are ingroups in which the impedances comprising a particular group are thesame but different from the impedances of another group.

18. A musical instrument of the class employing a keyboard, eachplaying-key of which is provided with a single electric switch which 1sactuable from an olf condition when the key is elevated to an oncondition when the key is lowered; said instrument comprising aplurality of electron-discharge devices respectively providing sourcesproducing output waves at tone frequencies for more than two octaves ofnotes of a musical scale, each of said electron-discharge devices havingan output terminal connected to a preassigned one of said switches, andimpedances interconnecting preassigned ones of said devices withpreassigned ones of said output terminals, whereby the output wave atsaid preassigned terminals is the sum of output waves from apredetermined number of said electron-discharge devices, the impedancesinterconnecting the preassigned terminals of some of saidelectron-discharge devices being the same but different from theimpedances of others of said devices.

19. A musical instrument of the class employing a keyboard, eachplaying-key of which is provided with an electric switch which isoperable from an olf condition when the key is elevated to an oncondition when the key is depressed, an audio amplifier having a loudspeaker connected in its output circuit; said instrument comprising,twelve sets of tone frequency oscillators, the oscillators of eachseparate set connected in cascade to produce octavely related tonefrequencies, said sets of cascaded oscillators arranged in separate notegroups, the oscillators o1' each set of cascaded oscillators having anoutput terminal connected in circuit with a preassigned one of saidelectric switches; resistive means for each set of cascaded oscillators,said resistive means comprising resistances interconnecting the outputterminals of the oscillators to each of said sets, the resistances inany given group of said cascades being the same but different from theresistances of any other group of cascades, a filter system having anoutput conductor connected to the input circuit of said audio amplifier,and a common conductor connecting all of the aforementioned electricswitches to the input side of said filter system.

MERWIN J. LARSEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,203,432 George June 4, 19402,227,100 Manatt Dec. 13, 1940 2,233,948 Kock Mar. 4, 1941 2,403,090Larsen July 2, 1946

